doc/rados/operations: add prompts to operating.rst
This commit adds ".. prompt:: bash $"-style prompts to operating.rst.
This brings this file up to the standard established in 2020 when
Kefu added support for the ".. prompt::" directive.
This commit is a part of an initiative to modernize the presentation
of all BASH commands in the RADOS documentation.
The progress of this project can be tracked here:
https://tracker.ceph.com/issues/57108